diff --git a/pkg/chain/chain.go b/pkg/chain/chain.go
index 2da29ff..aa857c9 100644
--- a/pkg/chain/chain.go
+++ b/pkg/chain/chain.go
@@ -10,7 +10,7 @@ import (
 )
 
 // ID is the ID of rule chain.
-type ID string
+type ID []byte
 
 // MatchType is the match type for chain rules.
 type MatchType uint8
diff --git a/pkg/chain/chain_easyjson.go b/pkg/chain/chain_easyjson.go
index c744878..fd7ff8c 100644
Binary files a/pkg/chain/chain_easyjson.go and b/pkg/chain/chain_easyjson.go differ
diff --git a/pkg/chain/marshal_binary.go b/pkg/chain/marshal_binary.go
index 343eca4..83e6380 100644
--- a/pkg/chain/marshal_binary.go
+++ b/pkg/chain/marshal_binary.go
@@ -19,7 +19,7 @@ var (
 func (c *Chain) MarshalBinary() ([]byte, error) {
 	s := marshal.UInt8Size // Marshaller version
 	s += marshal.UInt8Size // Chain version
-	s += marshal.StringSize(string(c.ID))
+	s += marshal.SliceSize(c.ID, func(byte) int { return marshal.ByteSize })
 	s += marshal.SliceSize(c.Rules, ruleSize)
 	s += marshal.UInt8Size // MatchType
 
@@ -34,7 +34,7 @@ func (c *Chain) MarshalBinary() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	offset, err = marshal.StringMarshal(buf, offset, string(c.ID))
+	offset, err = marshal.SliceMarshal(buf, offset, c.ID, marshal.ByteMarshal)
 	if err != nil {
 		return nil, err
 	}
@@ -72,11 +72,11 @@ func (c *Chain) UnmarshalBinary(data []byte) error {
 		return fmt.Errorf("unsupported chain version %d", chainVersion)
 	}
 
-	idStr, offset, err := marshal.StringUnmarshal(data, offset)
+	idBytes, offset, err := marshal.SliceUnmarshal(data, offset, marshal.ByteUnmarshal)
 	if err != nil {
 		return err
 	}
-	c.ID = ID(idStr)
+	c.ID = ID(idBytes)
 
 	c.Rules, offset, err = marshal.SliceUnmarshal(data, offset, unmarshalRule)
 	if err != nil {
diff --git a/pkg/chain/marshal_json.go b/pkg/chain/marshal_json.go
index 6039081..8dec214 100644
--- a/pkg/chain/marshal_json.go
+++ b/pkg/chain/marshal_json.go
@@ -143,11 +143,3 @@ func (ct *ConditionType) UnmarshalEasyJSON(l *jlexer.Lexer) {
 	}
 	*ct = ConditionType(v)
 }
-
-func (id ID) MarshalEasyJSON(w *jwriter.Writer) {
-	w.Base64Bytes([]byte(id))
-}
-
-func (id *ID) UnmarshalEasyJSON(l *jlexer.Lexer) {
-	*id = ID(l.Bytes())
-}
diff --git a/pkg/chain/marshal_json_test.go b/pkg/chain/marshal_json_test.go
index 75b1bc6..6c15ae9 100644
--- a/pkg/chain/marshal_json_test.go
+++ b/pkg/chain/marshal_json_test.go
@@ -38,11 +38,11 @@ func TestMatchTypeJson(t *testing.T) {
 		data, err := chain.MarshalJSON()
 		require.NoError(t, err)
 		if mt == MatchTypeDenyPriority {
-			require.Equal(t, []byte("{\"ID\":\"\",\"Rules\":null,\"MatchType\":\"DenyPriority\"}"), data)
+			require.Equal(t, []byte("{\"ID\":null,\"Rules\":null,\"MatchType\":\"DenyPriority\"}"), data)
 		} else if mt == MatchTypeFirstMatch {
-			require.Equal(t, []byte("{\"ID\":\"\",\"Rules\":null,\"MatchType\":\"FirstMatch\"}"), data)
+			require.Equal(t, []byte("{\"ID\":null,\"Rules\":null,\"MatchType\":\"FirstMatch\"}"), data)
 		} else {
-			require.Equal(t, []byte(fmt.Sprintf("{\"ID\":\"\",\"Rules\":null,\"MatchType\":\"%d\"}", mt)), data)
+			require.Equal(t, []byte(fmt.Sprintf("{\"ID\":null,\"Rules\":null,\"MatchType\":\"%d\"}", mt)), data)
 		}
 
 		var parsed Chain
@@ -55,7 +55,7 @@ func TestMatchTypeJson(t *testing.T) {
 
 func TestJsonEnums(t *testing.T) {
 	chain := Chain{
-		ID:        "2cca5ae7-cee8-428d-b45f-567fb1d03f01", // will be encoded to base64
+		ID:        []byte("2cca5ae7-cee8-428d-b45f-567fb1d03f01"), // will be encoded to base64
 		MatchType: MatchTypeFirstMatch,
 		Rules: []Rule{
 			{
diff --git a/pkg/engine/inmemory/local_storage.go b/pkg/engine/inmemory/local_storage.go
index 21d3d55..30553bd 100644
--- a/pkg/engine/inmemory/local_storage.go
+++ b/pkg/engine/inmemory/local_storage.go
@@ -1,6 +1,7 @@
 package inmemory
 
 import (
+	"bytes"
 	"fmt"
 	"math/rand"
 	"strings"
@@ -14,14 +15,14 @@ import (
 type targetToChain map[engine.Target][]*chain.Chain
 
 type inmemoryLocalStorage struct {
-	usedChainID          map[chain.ID]struct{}
+	usedChainID          map[string]struct{}
 	nameToResourceChains map[chain.Name]targetToChain
 	guard                *sync.RWMutex
 }
 
 func NewInmemoryLocalStorage() engine.LocalOverrideStorage {
 	return &inmemoryLocalStorage{
-		usedChainID:          map[chain.ID]struct{}{},
+		usedChainID:          map[string]struct{}{},
 		nameToResourceChains: make(map[chain.Name]targetToChain),
 		guard:                &sync.RWMutex{},
 	}
@@ -35,12 +36,13 @@ func (s *inmemoryLocalStorage) generateChainID(name chain.Name, target engine.Ta
 		sid = strings.ReplaceAll(sid, "*", "")
 		sid = strings.ReplaceAll(sid, "/", ":")
 		sid = strings.ReplaceAll(sid, "::", ":")
-		id = chain.ID(sid)
-		_, ok := s.usedChainID[id]
+		_, ok := s.usedChainID[sid]
 		if ok {
 			continue
 		}
-		s.usedChainID[id] = struct{}{}
+		s.usedChainID[sid] = struct{}{}
+
+		id = chain.ID(sid)
 		break
 	}
 	return id
@@ -51,7 +53,7 @@ func (s *inmemoryLocalStorage) AddOverride(name chain.Name, target engine.Target
 	defer s.guard.Unlock()
 
 	// AddOverride assigns generated chain ID if it has not been assigned.
-	if c.ID == "" {
+	if len(c.ID) == 0 {
 		c.ID = s.generateChainID(name, target)
 	}
 	if s.nameToResourceChains[name] == nil {
@@ -59,7 +61,7 @@ func (s *inmemoryLocalStorage) AddOverride(name chain.Name, target engine.Target
 	}
 	rc := s.nameToResourceChains[name]
 	for i := range rc[target] {
-		if rc[target][i].ID == c.ID {
+		if bytes.Equal(rc[target][i].ID, c.ID) {
 			rc[target][i] = c
 			return c.ID, nil
 		}
@@ -80,7 +82,7 @@ func (s *inmemoryLocalStorage) GetOverride(name chain.Name, target engine.Target
 		return nil, engine.ErrResourceNotFound
 	}
 	for _, c := range chains {
-		if c.ID == chainID {
+		if bytes.Equal(c.ID, chainID) {
 			return c, nil
 		}
 	}
@@ -99,7 +101,7 @@ func (s *inmemoryLocalStorage) RemoveOverride(name chain.Name, target engine.Tar
 		return engine.ErrResourceNotFound
 	}
 	for i, c := range chains {
-		if c.ID == chainID {
+		if bytes.Equal(c.ID, chainID) {
 			s.nameToResourceChains[name][target] = append(chains[:i], chains[i+1:]...)
 			return nil
 		}
diff --git a/pkg/engine/inmemory/local_storage_test.go b/pkg/engine/inmemory/local_storage_test.go
index 3609070..5c37879 100644
--- a/pkg/engine/inmemory/local_storage_test.go
+++ b/pkg/engine/inmemory/local_storage_test.go
@@ -14,9 +14,7 @@ const (
 	nonExistChainId = "ingress:LxGyWyL"
 )
 
-var (
-	resrc = engine.ContainerTarget(container)
-)
+var resrc = engine.ContainerTarget(container)
 
 func testInmemLocalStorage() *inmemoryLocalStorage {
 	return NewInmemoryLocalStorage().(*inmemoryLocalStorage)
@@ -210,12 +208,12 @@ func TestGenerateID(t *testing.T) {
 }
 
 func hasDuplicates(ids []chain.ID) bool {
-	seen := make(map[chain.ID]bool)
+	seen := make(map[string]bool)
 	for _, id := range ids {
-		if seen[id] {
+		if seen[string(id)] {
 			return true
 		}
-		seen[id] = true
+		seen[string(id)] = true
 	}
 	return false
 }
diff --git a/pkg/morph/policy/policy_contract_storage.go b/pkg/morph/policy/policy_contract_storage.go
index 2e0a756..2eaa099 100644
--- a/pkg/morph/policy/policy_contract_storage.go
+++ b/pkg/morph/policy/policy_contract_storage.go
@@ -44,7 +44,7 @@ func NewContractStorageWithSimpleActor(rpcActor actor.RPCActor, acc *wallet.Acco
 }
 
 func (s *ContractStorage) AddMorphRuleChain(name chain.Name, target engine.Target, c *chain.Chain) (txHash util.Uint256, vub uint32, err error) {
-	if c.ID == "" {
+	if len(c.ID) == 0 {
 		err = ErrEmptyChainID
 		return
 	}
@@ -61,7 +61,7 @@ func (s *ContractStorage) AddMorphRuleChain(name chain.Name, target engine.Targe
 }
 
 func (s *ContractStorage) RemoveMorphRuleChain(name chain.Name, target engine.Target, chainID chain.ID) (txHash util.Uint256, vub uint32, err error) {
-	if chainID == "" {
+	if len(chainID) == 0 {
 		err = ErrEmptyChainID
 		return
 	}